Technical Field
The present invention relates to a hydraulic circuit for a construction machine and control device therefor.
Description of Related Art
Among construction machinery, there is one that performs controls for returning a portion of pressure oil discharged from a hydraulic pump to a hydraulic oil tank (bleed-off control). In order to perform the bleed-off control, a construction machine may have a gap (bleed opening) provided in a spool of a direction control valve for returning the pressure oil. By changing the opening area of the bleed opening, the construction machine performs bleed control.
With a hydraulic circuit for a construction machine according to a related art, a spool of a direction control valve Vm is provided with multiple bleed openings Sbo as illustrated in, for example, FIG. 6. In this case, the hydraulic circuit performs bleed-off control by changing the opening area of the bleed opening Sbo.